I can include this figure but I have to convert it to eps first (with the "convert" command), then there is no problem, but I'm afraid the final pdf will be too heavy if I convert all my graphics to eps... does someone knows how to fix this problem of bounding box, or tell me if i'm doing something wrong?

latex doesn't accept PNG files. You should go the other way and convert EPS files to PDF with epstopdf or "on the fly" with the epstopdf package. You then can compile your document source with pdflatex and include your PNG files as usual.

Thanks for your fast reply!but I'm very surprised with what you said: I'm a begginer in latex, but a single google search "latex png" gives a lot of results where we can see people explaining that they use png in their latex documents... but I must be confused between latex, pdflatex, texshop and others tex.

Then I will do as you suggest, but is there a way to make the final document not so heavy in terms of memory? I only did one chapter and it is already 8Mo!

timbrochier wrote:[…] but a single google search "latex png" gives a lot of results where we can see people explaining that they use png in their latex documents... but I must be confused between latex, pdflatex, texshop and others tex. […]

Obviously, you are a little bit confused. LaTeX is the typesetting system, which has (amongst others) the two compilers latex and pdflatex. The first one produces DVI output, the second has PDF as output format. latex only accepts PS/EPS files for graphics inclusion. pdflatex accepts JPG, PNG and finally PDF format. Since you are running a Mac System, you even can include TIF files when compiling with pdflatex.

timbrochier wrote:[…] Then I will do as you suggest, but is there a way to make the final document not so heavy in terms of memory? I only did one chapter and it is already 8Mo!

The size of the final output should not reach this mark. The PNG files converted to EPS blow up the file. This should not happen when leaving them untouched and process the EPS files as described in my first reply.

The advantage of converting the EPS files is that the vector based character of the files is kept, whereas the pixel based PNG format must be converted to a vector format. This yields the large size of the resulting files.